This is a basic economic principle (but like many economic principles it’s not well understood [or even defined]) that basically states people evaluate whether or not the positive outweighs the negative.
For teachers the reward has always been pretty small. Our paychecks are unimpressive at every scale. Our benefits are likewise. Even the vaunted summer vacation that everyone points to is really nothing. Most teachers spend their summers in preparation for the next school year by developing curriculum or attending workshops and seminars. Also, since the paycheck is unimpressive, many teachers elect to do summer school in order to make ends meet.
The reward was always stacked by one thing, students who learned. We take joy at watching students learn and excel, knowing we’ve made a difference in their lives. These students have never been the majority, either, but they were enough to keep us going.
I sense that shifting. It’s no longer enough for many of us. It’s a dying profession, one that will not attract the types of teachers the students need, but rather the ones that make themselves popular and easy.